Plaque assay

Definition

A plaque assay is a laboratory technique used to quantify the number of virus particles present in a sample by measuring the number of plaques formed on a layer of host cells. This method is particularly important for studying bacteriophages, which are viruses that infect bacteria, and allows researchers to determine viral concentration and assess the effects of different variables on viral replication and infection.

5 Must Know Facts For Your Next Test

1. The plaque assay is essential for quantifying bacteriophages, enabling scientists to determine the number of infectious virus particles in a given sample.
2. Each plaque corresponds to a single virus particle that has infected a host cell and led to its lysis, providing a visual representation of viral activity.
3. This technique involves diluting the viral sample, mixing it with host bacteria, and allowing it to incubate to form visible plaques on an agar plate.
4. Plaque assays can also be used to test the efficacy of antiviral agents or conditions that may inhibit viral replication.
5. Results from plaque assays can help in characterizing bacteriophages for therapeutic applications, including phage therapy as an alternative to antibiotics.

Review Questions

• How does a plaque assay work and what does it measure?
  • A plaque assay works by diluting a viral sample and mixing it with a layer of host bacteria on an agar plate. After incubation, each virus particle that successfully infects a host cell creates a visible plaque, which is a clear area where the cells have been lysed. By counting the number of plaques formed, researchers can measure the concentration of infectious virus particles in the original sample, providing valuable data on viral activity and replication.
• Discuss how plaque assays can be used to evaluate the effects of antiviral treatments on bacteriophages.
  • Plaque assays are effective tools for evaluating antiviral treatments because they allow researchers to observe changes in viral replication rates in response to various compounds. By applying different concentrations of antiviral agents to cultures with bacteriophages, scientists can compare the number of plaques formed in treated versus untreated samples. A decrease in plaque formation indicates that the antiviral treatment has successfully inhibited viral activity, providing insights into its effectiveness.
• Evaluate the significance of plaque assays in advancing phage therapy as an alternative treatment for bacterial infections.
  • Plaque assays play a pivotal role in advancing phage therapy by enabling researchers to isolate and characterize specific bacteriophages that can target pathogenic bacteria. Through quantifying viral loads and assessing their effectiveness against bacterial strains, scientists can identify promising phage candidates for therapeutic use. This information is critical in developing phage therapies as an alternative treatment strategy amidst rising antibiotic resistance, showcasing the potential of bacteriophages in modern medicine.

Related terms

Bacteriophage: A type of virus that specifically infects and replicates within bacteria, playing a crucial role in bacterial ecology and evolution.

Plaque: An area of cleared or lysed cells on a lawn of host cells caused by the infection and subsequent lysis due to viral replication.

Titer: The concentration of virus in a solution, often expressed as the number of infectious units per volume.